<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8"/>
        <title>01test</title>
        <script src="js/jquery-1.12.4.min.js"></script>
    </head>
    <body>
        <div></div>
    </body>
    <script>
        $( function () {
            $('div').attr('title','this is a div');
            $('div').attr('class','box');
            $('.box').css('background','blue');
            $('.box').html('123');
        } )
    </script>
</html>